The field of telecommunications experienced an explosive growth in the last decade of the 20th century. Optical networking came to the forefront as being the technology of choice for some long-haul communications applications.
One of the advancements in optical networking during that time was the continuing development of the optical amplifier. Currently, optical amplifiers are widely used in today's fiber optic networks to amplify weakened signals. The invention of the optical amplifier made wavelength division multiplexing (WDM) possible. With optical amplifiers, repeaters can simultaneously amplify transmission signals transmitted through multiple optical wavelengths without the need to demultiplex the signals, convert each signal into an electrical signal, regenerate and then remultiplex the signals.
However, with the advancement in technology and materials, the cost of amplifiers has dropped dramatically, almost 10 times in the past 8 years. This steep decline in price renders single wavelength amplification a viable solution in certain applications such as those which involve extremely high data rates. These high data rates may lead to transmitters outputting weaker signals compared to lower data rates.
In these and other transmission systems, optical amplifiers have always been a fixed component. If the amplifier becomes defective, the whole circuit card containing the amplifier needs to be replaced.
Optical amplifiers also have a slight drawback in that they are uni-directional by nature. In most amplifiers, there is an input and an output. However, in the real world, signals propagate in a minimum of one fiber pair—one fiber for east to west, and another fiber for west to east.
Optical amplifiers also have another drawback—they have a weakness which causes optical transients when its input undergoes a sudden change. In a previous invention, there was disclosed a method to counter such optical transients (most often caused by fiber a cut). The large transient is especially damaging to optical receivers due to the limited range accepted by the receiver. For example, a 10 Gigabit receiver has an upper receiving power limit of −8 dBm. However, when there is an optical transient, the peak power may reach well beyond 0 dBm momentarily, causing the receiver not only to become saturated, but also causing the destruction of the receiver's internal semiconductor structure by the large pulse.
There is therefore a need for devices and systems which mitigate if not overcome the shortcomings of the prior art.